A 64-year-old man with idiopathic CD4(+) lymphocytopenia developed cognitive impairment and gait ataxia with isolated obstructive hydrocephalus, which was fatal. Cerebrospinal fluid showed mild pleocytosis, but the etiology was not revealed by extensive analysis. At autopsy, inflammatory cells, CD8(+) lymphocytes and abundant macrophages but not CD4(+) lymphocytes were infiltrating the meninges at the base of the brain. Electron microscopy demonstrated that inflammation was caused by Cryptococcus neoformans, which was localized exclusively within macrophages, where it grew with budding. Our study suggests that, in idiopathic CD4(+) lymphocytopenia, macrophages can efficiently phagocytize but inefficiently digest C. neoformans, thus representing a vehicle of chronic intracellular infection.